Switch mechanism



1955 G. T. RANDOL 2,716,678

SWITCH MECHANISM Original Filed June 9, 1952 United States Patent Ofiice 2,716,67fi Patented Aug. 30, 1955 SWITCH MEQHANISM Glenn T. Randal, Mountain Lake Park, Md.

Continuation of application Serial No. 292,550, June 1952. This application March 17, 1954, Serial No. 416,808

9 Claims. c1. zoo-urea The present invention relates to a novel switch mechanism designed for incorporation in an electrical circuit. This is a continuation or" my prior co-pending application Serial No. 292,550, filed June 9, 1952, now abandoned.

Broadly, this invention concerns a switch mechanism for selectively opening or closing an electrical circuit adapted to control the operation of an energizable apparatus or the like, the latter situated either approximately or remotely relatively to said mechanism.

More specifically, my invention is directed to the provision of a novel switch mechanism operable by minute reciprocable movements of an element which may be actuated, for example, by an automotive accelerator pedal, by a servomotor piston, by mechanical linkage, or by manual-or speed-responsive means.

Preferably, but not necessarily, the switch mechanism comprising the present invention is pivotally mounted, so as to compensate readily for corresponding movements of a reciprocable or oscillatable operating or actuating element, as will appear.

The primary objects of my invention therefore, are the provision of a compact and simple switch mechanism responsive to minute reciprocal movements of an actuatable element, for selectively closing and opening an electrical circuit at any point along the full operating stroke of said element; the provision of means for suitably mounting said switch mechanism on a support to accommodate actuation thereof; the provision of means incorporated in said mechanism for accommodating minute movements of the actuating element without affecting the then existent relative disposition of the circuit closing elements; and the provision of means for normally maintaining the switch mechanism in circuitclosing position.

A further and important object of the invention related to the series of primary objects immediately preceding, is the provision of means to accommodate a full operating stroke of the actuatable element relative to either a closed, or an open position of an included movable contact assembly, and wherein said movable contact assembly is operatable to closed and open positions substantially at all points along the full stroke of the actuatable element responsive to minute reciprocable movements of said element within its operating stroke aforesaid, thus to produce in effect, a followup control of the energization and de-energization of a device controlled by the circuit.

Another object relative to that immediately preceding, is the provision of novel means to enable continued movement of the actuatable element in one direction after the movable contact assembly has been moved to open position, without affecting the open disposition of the assembly; to enable continued movement of the actuatable element in the opposite direction after the movable contact assembly has been moved to closed position, without affecting the closed disposition of the assembly; and to enable arrested movements of the actuatable element during the full stroke thereof in either direction, without affecting the then obtaining disposition of said contact assembly.

A further and more specific object related to the two immediately preceding objects, resides in the utilization of an automotive vehicle engine accelerator mechanism as the personal responsive means for actuating the actuatable element of the switch mechanism, the latter including means for accommodating the full stroke of the accelerator throughout its engine controlling range of movement, and adapted responsive to minute reciprocations of said accelerator transmitted to said actuatable element, to operate the switch mechanism for opening and closing the circuit of a power device, whereby to control the operation thereof and thus provide in effect, a followup control therefor.

In the more comprehensive and detailed description to follow, features and advantages not specifically recited hereinbefore will be apparent or noted, reference being had also to the accompanying drawing in which the preferred embodiment of my invention is illustrated.

In the drawings:

Figure 1 is a diagrammatic layout of a servomotor control system wherein is incorporated the switch mechanism comprising the present invention;

Figure 2 is an enlarged horizontal sectional view of said switch mechanism in closed contact position, taken along the line 2-2 of Figure 1;

Figure 3 is a vertical sectional line 3-3 of Figure 2;

Figure 4 is a further enlarged reproduction of the major portion of Figure 2, the switch being shown in open contact position; and

Figure 5 is a perspective view of the movable contact assembly of the switch mechanism.

Referring to the drawings:

The switch mechanism comprising the instant invention is designated in its entirely by the numeral 8, and its incorporation in a servomotor system, generally designated It), has been resorted to for illustrating and explaining the novel construction and operation thereof.

The illustrated switch actuating element of said system comprises, by way of example, a rod 12 reciprocable by means of a pedal 14 in conjunction with a compression spring 16, as should be apparent from an inspection of Figure 1.

It is here noted that the rod 12 typifies any similar reciprocable element characterized by axial or rotational movement, either mechanically or manually actuatable to effect the operation of the switch mechanism in a novel manner to be described.

The switch mechanism 8 as seen to best advantage in Figures 2 and 3, includes a cup-shaped casing generally designated 18; a movable contact assembly generally designated 20; a fixed contact assembly generally designated 22; a preloaded compression spring 24; an elongated split friction sleeve 26; and a pivotal mounting for the mechanism generally indicated 28.

The cup-shaped casing 18 includes a cylindrical body portion 30; an end wall 32; a projecting sleeve portion 34 integral with the latter; and an outturned circular flange 36 integral with said body portion.

The movable assembly 20 includes a pair of non-metallic members 38 and 4t) united by a metallic contact member 42, the non-metallic elements being of fibrous or hard rubber composition.

The member 33 is tubular and includes a first sleeve segment 44 slidable on the rod 12; a second larger diametered sleeve segment 46 surrounding the collar 26 but not in contact therewith; an annular shoulder 48 joining said sleeve segments; and an outturned circular view taken along the flange 50 on the shoulder opposed end of the segment 46.

The member 40 includes a disk segment 52 integral with a sleeve segment 54, the latter slidable on the rod 12, and the peripheral margin of the former coinciding with a similar portion on the flange 5G. The metallic Contact member 42, initially an annulus, is spun about said disk and flange so as to unite them as clearly shown, and to provide an annular abutment designated 56 for one end of the split sleeve 2s, as will appear.

The assembly 22 includes a circular mounting plate 58 the diameter of which coincides with that of flange 36; a projecting annular flange 69 integral with the plate and slidably receiving the rod 12; a pair of diametrically opposite contact elements 62; insulation 64- provided about said contacts to segregate them electrically from the metallic casing 18 and the plate 58; and a plurality of rivets 66 or the like for permanently securing the plate to the flange 36 of the casing 18.

Compression spring 24 is of conical configuration as portrayed, and has its large end seated against the end wall 32 of casing 18, with its small end bearing against shoulder 48 of the tubular member 33.

In its normal or collapsed condition, the internal diameter of the split sleeve 26 is slightly smaller than the external diameter of the rod 12. Consequently, when the sleeve is assembled in deformed condition on said rod, it inherently exerts a frictional or slight clamping action thereupon, as is understood.

With particular reference to Figure 2, it is seen that the sleeve 34 is pressfitted into a circular depression 6 3 provided in a block 70, and that the free end of rod 12 terminates in an enlarged cylindrical portion 72, the latter slidable in said sleeve and in an aligned bore 74 formed in said block. Numeral 75 indicates an annular shoulder defining the juncture between the rod proper, and the enlarged portion 72 thereof.

Projecting laterally from block 7%, is an integral trunnion 76 included in the pivotal mounting 28. Numeral 78 designates a stationary supporting structure having a projecting boss 80, the latter provided with a socket 82 for the reception of the trunnion 76. Formed in said trunnion is an annular groove 84 which is engaged by a pin 86 the ends of which are seated in aligned apertures provided in boss 80. Thus it should be apparent that the switch mechanism 8 is retained against fortuitous displacement from its selected pivotal mounting.

As hereinbefore noted, the switch mechanism 8 is illustrated in Figure l, for explanatory purposes, as incorporated in a servomotor control system 10. Said system includes, in addition to the structure already enumerated: a vacuum tank T; a solenoid operable valve SV in fluid communication therewith; a servomotor SM in fluid communication with the solenoid valve; and a circuit including a manual switch MS, a lead 38 extending between said switch and one of the terminals 62, a battery B, a lead L extending between switch MS and the battery, and a lead extending between the other terminal 62 and one terminal of the solenoid valve. The other terminal of said valve is grounded at G, as is the battery B to complete the circuit.

The tank T, the valve SV, and the servomotor SM are of conventional design, so that it is not considered necessary to describe them in detail. However, for a better understanding of the subsequent description of operation, it is believed advisable to alphabetically designate the most pertinent elements.

Thus, the valve proper of solenoid valve SV is designated a; the piston of the servomotor SM is designated b; its piston rod is designated c; a compression return spring is indicated :1; a breather cap e; and a pivotal mounting for the unit SM is indicated at f.

The letter s designates a rotatably mounted shaft, the rotation of which in either direction is controlled by the movements of piston rod c, which is shown to have a pivotal connection g with a link It, the latter rigid with one end of said shaft. It is noted that the shaft 5 is typical of any similar element the rotation of which is responsive to the action of said system under the influence of the switch mechanism 3.

In other words, the shaft s may serve, for example, as the operating element of an automobile braking system, or as the control member for a friction clutch. Again, the shaft s may represent a rotatable member for raising and lowering a radio antenna, and so on. it is also noted that the pedal 14 is typical of any suitable means, either mechanically or manually operable, for imparting reciprocatory motion to the rod 12.

It will be assumed that the shaft s constitutes the control for a conventional friction type clutch of an auto motive vehicle. The illustrated servomotor system ill exhibits the normal status of the included mechanical and electrical components when the engine of said vehicle is idling, and the switch MS is closed.

At such time, the valve a is in open position whereby the thus established vacuum factor obtaining between tank T, solenoid valve SV, and servomotor SM maintains the piston b rearwardly against the forwardly biasing force of compression return spring d, as should be apparent. Consequently, assuming that the portrayed disposition of link It indicates a clutch-disengaged status, the status quo will continue to obtain so long as the rod 12 is not perceptibly, that is positively activated.

In other words, and with particular reference to Figure 2, the metallic member 42 of the assembly 20 is shown maintained in firm circuit-closing contact with the elements 62 by means of shoulder 75 hearing against the end of sleeve segment 44 under the influence of compression spring 16. That is to say, in biasing the pedal 14 upwardly to its normal full line position, the spring to simultaneously biases the rod 12 in the same direction, so that the movable contact assembly is firmly seated between the shoulder 75 and the contact elements 62.

Whenever said pedal is in its normal position, the right end of friction sleeve 26 as viewed in Figures 2 and 3, is engaged against the annular abutment 56. It is noted however, that the space obtaining between said abutment and the shoulder 43 is greater that the length of sleeve 26, so that a minute lost-motion arrangement is provided.

That is to say, a slight depression of pedal 14, as suggested by the broken line position appearing immediately adjacent the full line position thereof, will not affect the existent circuit-closing relation of the member 42 and the contact elements 62, because during the concurrent slight movement of sleeve 25 away from the abutment 56, the compression spring 24 per se will continue to bias the assembly 20 to the right into engagement with said contact elements.

Therefore, it is only when the pedal 14 is positively depressed, for example from the said full line position to the second suggested broken line position thereof, that the fully open contact position of the switch mechanism demonstrated in Figure 4 is had.

In this connection, it is noted that the frictional coefficient obtaining between sleeve 26 and rod 12 is sufiiciently great to overcome the inherent expansion of compression spring 24.

Consequently, as the pedal is being positively depressed from the first to the intermediate broken line position thereof, the left end of split sleeve 26 first engages against the shoulder 48 of contact assembly 20, and thereupon moves said assembly leftwardly against the force of spring 24, whereby to separate the member 42 from the elements 62.

When the left end of sleeve 26 engages against the shoulder 48, an annular gap is formed about the rod 12 between the extremity of segment 44 and shoulder 75 of the enlarged rod portion 72, but thereafter the rod and the assembly 20 move leftwardly in unison until the sleeve segment 44 engages against the wall 32 of the casing 18, as in Figure 4. Should the pedal be further depressed that is to its final arrested broken line position, the existent fully open disposition of the movable contact assembly would not be disturbed. In other words, only the rod 12 and its enlarged portions 72 could and would move relatively with respect to sleeve 26 farther leftwardly, so that the split sleeve 26 would be farther removed from the shoulder 75, as is obvious.

As soon as the circuit is broken, solenoid valve SV is obviously de-energized to close the valve proper a. As a result, the compression spring d biases the piston b forwardly, the servomotor being vented via breather cap e. Consequently, shaft .9 is rotated counterclockwise from its illustrated position, to effect engagement of the exemplary clutch. This clutch-engaged status will continue so long as the pedal is sufliciently depressed to maintain the switch open.

That is to say, a slight release due to vehicular vibration and so on, will not ordinarily disturb the clutchengaged status quo, because of the lost-motion arrangement and the annular gap aforesaid. However, it is noted that the invention provides a novel and eifective mechanism for intermittently opening and closing a circuit with the pedal in an approximately intermediate, or at substantially any position along its full operating stroke, to produce in eifect, an operational result simulating a followup control of the associated power device.

Thus for example, reverting to Figure 4 it is seen that the split sleeve 26 is engaged at one end against the shoulder 48 to maintain the movable contact assembly 2% in its fully open position. It will be remembered that Figure 4 is illustrative of a switch status which may obtain at any depressed stage of the pedal 14 intermediate its two extreme positions.

Consequently, assuming that said pedal is now released slightly, the other end of split sleeve 26 will automatically engage against the annular abutment 56 to move the assembly 20 to a closed position, with the contact member 42 thereof bridging the fixed contacts 62.

Assuming now that the pedal is again depressed slightly, the sleeve 26 will again strike against the shoulder 48 to reopen the switch. Thus, it should be manifest that rapid intermittent openings and closings of the control circuit may be effected at any intermediate position of the pedal by the alternate release and depression thereof, irrespective of the then obtaining disposition of the split sleeve 26 relative to the shoulder 75. It should further be manifest that complete release of pedal 14 from any intermediate depressed position thereof, will automatically cause the switch mechanism to revert to its Figure 2 disposition.

From the foregoing description augmented by an in spection of the drawings, it should be manifest that my invention provides a novel switch mechanism which is particularly adapted for incorporation in a servomotor control system and the like.

However, it is to be understood that the illustrated and described control system has been given by way of example only, and not in a limiting sense. In said exemplary system, the pivotal mounting 28 is obviously requisite. Such an arrangement may not be necessary should the actuating rod 12 be reciprocated along a constant plane.

Therefore, I do not desire to be restricted to the precise details illustrated and described, my invention contemplating any and all modifications thereof, and such equivalents as may fall within the scope of the appended claims.

What I claim is:

1. In a switch mechanism including a pair of fixed contacts and a cooperating movable contact assembly, means for normally biasing said movable assembly into engagement with the fixed contacts to close an electrical circuit, and reciprocable means for moving said assembly out of engagement with the fixed contacts to open said 6 circuit: means responsive to minute reciprocations of the reciprocable means at any selected position intermediate the limits of the operating stroke thereof for alternately moving said assembly into and out of engagement with said contacts.

2. in a switch mechanism including a pair of fixed contact elements and a cooperating movable contact assembly, means for biasing said movable assembly into engagement with said contact elements to normally maintain an electrical circuit closed, and reciprocable means for first moving said assembly out of engagement with said contact elements to temporarily maintain said circuit open, and for subsequently returning said assembly to its contact-engaging position to reclose said circuit: means responsive to minute reciprocations of the reciprocable means for alternately moving said assembly into and out of engagement with said contact elements at any selected position intermediate the limits defining the operating stroke of said reciprocable means.

3. In a switch mechanism including a casing, an annular plate rigid with one end thereof, a pair of fixed contacts mounted on said plate, and a reciprocable rod slidably supported in the casing: the combination of a contact assembly movable axially along said rod into and out of engagement with said contacts for opening and closing an electrical circuit, an elongated split sleeve member frictionally engaged about a portion of the rod within said assembly for moving the latter when said rod is reciprocated, and a preloaded compression spring interposed between a portion of said casing and a shoulder portion of said assembly for stabilizing the latter during reciprocal movements of said rod; the said contact assembly comprising first and second non-metallic elements united by a metallic contact member, the first non-metallic element including integrally: a sleeve segment slidable on said rod, a larger diametered sleeve segment surrounding said elongated split sleeve member but not in contact therewith, an annular shoulder joining the sleeve segments, and an outturned circular flange on the shoulder opposite end of the larger sleeve segment; the second nonmetallic element including integrally: a disk segment the periphery of which coincides with that of the circular flange of the first element aforesaid, and a sleeve segment slidable on said rod; the metallic contact member comprising an annulus spun about said circular flange and disk to unite them and to simultaneously provide an abutment for one end of the elongated split sleeve member.

4. Switch mechanism for controlling the opening and closing of an electrical circuit, said mechanism including in combination: a pair of diametrically opposed stationary contacts; a cooperating movable contact assembly for simultaneously engaging said contacts; a reciprocable rod and an elongated split sleeve member frictionally associated therewith for moving the contact assembly out of engagement with said contacts to open the circuit when said rod is actuated in one direction, and for moving said assembly into engagement with said contacts to close the circuit when said rod is actuated in the opposite direction; means for normally maintaining said movable contact assembly in engagement with said stationary contacts when the reciprocable rod is inactive; and lostmotion means compensating for a slight initial movement of said rod in one direction without affecting said normally existent disposition of the contact assembly.

5. Switch mechanism for controlling the opening and closing of an electrical circuit, said mechanism including: a cup-shaped casing; a centrally apertured circular plate closing the open end of said casing; a pair of diametrically opposite contact elements mounted on said plate; insulation about said contacts to segregate them electrically from the plate; a reciprocable rod slidably supported in the casing and plate having a predetermined operating stroke between two extreme positions; a movable contact assembly slidably mounted on said rod within the casing;

means on said rod for normally maintaining the movable assembly in engagement with the contact elements; and an elongated split sleeve frictionally maintained in place on said rod within a sleeve portion of the movable assembly between an annular abutment and an annular shoulder thereof for moving said assembly out of engagement with said contacts when the rod is actuated in one direction, and for returning said assembly into engagement wth said contacts when the rod is actuated in an opposite direction, the internal diameter of the split sleeve in its normal collapsed state being slightly smaller than the external diameter of said rod, and the distance obtaining between the abutment and shoulder portions of the movable assembly sleeve being greater than the length of the split sleeve aforesaid.

6. The switch mechanism defined in claim 5 wherein the recited reciprocable rod terminates at one end in an enlarged cylindrical portion whereby to form an annular shoulder normally engaging against the recited sleeve of the movable contact assembly to maintain the latter in engagement with the said diametrically opposite contact elements.

7. In a switch mechanism including a fixed contact element and a cooperating contact assembly movable relatively to two operating positions with respect to the fixed contact element for controlling the condition of an associated electrical circuit: means for normally biasing said movable assembly to one of its operating positions; reciprocable means for moving said movable assembly to its other operating position; and means responsive to minute reciprocations of the reciprocable means at any selected position thereof intermediate the limits defining its full operating stroke for alternately moving said movable assembly between its two operating positions for controlling the condition of said electrical circuit.

8. The switch mechanism as defined in claim 7 in which the movable contact assembly includes means cooperatable with said last-named means for establishing limited lost-motion movement between said reciprocable means and said movable contact assembly.

9. The switch mechanism as defined in claim 8 in which said cooperatable means is efiective responsive to said reciprocable means moved to take up said lost-motion for releasing said reciprocable means from said responsive means, whereby movement of said reciprocable means in the same direction relatively to said movable contact assembly is accommodated to either of the limits of its full operating stroke without disturbing the then existent operating position of the latter.

No references cited. 

